Investigating the Functions of Rough-and-Tumble Play in American Mink, Neovison vison

Investigating the Functions of Rough-and-Tumble Play in American Mink, Neovison vison

Author:

Ahloy Dallaire, Jamie

Department:

Department of Animal Biosciences

Program:

Animal and Poultry Science

Advisor:

Mason, Georgia

Abstract:

Play is very widespread among young mammals, yet its functions remain mysterious. Ethologists have largely relied on social deprivation experiments or correlational studies to determine how play might promote survival or reproduction. Using American mink (Neovison vison) as a model, I aimed to develop an alternative experimental approach, not relying on deprivation, to test two hypotheses about the functions or long-term benefits of rough-and-tumble play: that it prepares animals to cope emotionally with unexpected, frightening situations, and that it prepares them for adult sexual behaviour. I aimed to do this using longitudinal studies of mink raised in multiple different housing treatments that independently modulate the frequency of rough-and-tumble play. If treatments have convergent effects on juvenile play and adult outcomes, then we may confidently ascribe these outcomes to differential juvenile play, rather than to other confounding effects of treatments on juveniles. In Chapter 2, in preliminary research into the basics of mink play, I showed that rough-and-tumble play is subject to modest litter effects, only somewhat stable over the juvenile period, and motivationally distinct from object play in mink. In Chapter 3, in research conducted over three summers, I tested a wide variety of experimental housing treatments but found none that had consistent effects on rough-and-tumble play frequency. In subsequent chapters, I was therefore limited to correlational, and not experimental, hypothesis tests. In Chapter 4, I found no evidence for a relationship between juvenile rough-and-tumble play and adult fearfulness. The most playful juveniles were no less likely to react fearfully to an experimenter’s approach or to scream when handled, and did not have smaller increases in corticosteroid hormone production when restricted in a carrying cage. In Chapter 5, I found that the most playful juvenile males copulated for longer durations in adulthood, but that the most playful females were slower or less likely to begin copulating with males. To my knowledge, these are the first demonstrations that juvenile rough-and-tumble play predicts adult sexual behaviour in any species. Further refinement of experimental methods will be required to understand whether and how rough-and-tumble play affects the sexual development of juvenile mink.